Modern Biology Began In The New York 'Fly Room'

When you hear about the history of genetics, it tends to start with Gregor Mendel's pea plants. Published exactly 150 years ago, the monk's breeding experiments went unappreciated until his work was rediscovered in 1900.

But the science of genetics as we know it today actually originated a decade later – in Room 613 of Schermerhorn Hall at Columbia University in New York City, in a tiny laboratory known as the 'fly room'.

The lab was just 5 metres long and 7m wide (16 x 23 feet) and contained eight desks covered with insect bottles. In the early days, a bunch of bananas would hang in the corner, making the room smell of fermenting fruit.

'The Fly Room' movie poster (Image: Imagine Science Films)

I recently got to see The Fly Room, an independent film about the birthplace of 20th-century genetics. The movie is mainly a biopic of Calvin Bridges, a young researcher in the lab led by pioneering American biologist Thomas Hunt Morgan.

Morgan spent many years studying the fruit fly Drosophila melanogaster. In 1910, he came across a new mutation that changed eye color from red to white. Like humans, male flies have distinct sex chromosomes – X and Y – whereas females have XX. Morgan realized that because the mutation only affected males, genes must be carried on chromosomes.

Based on the fact offspring inherit new combinations of traits from their parents, Morgan proposed that genes are arranged on a chromosome like beads on a string. He suggested that new gene combinations arise by crossing-over and exchange of genetic material between a pair of chromosomes. This is the foundation of the chromosome theory of heredity.

Diagram showing crossing-over and exchange of genetic material between two chromosomes, from the 1916 book 'A Critique of the Theory of Evolution' by Thomas Hunt Morgan (Image: Wikimedia)

Morgan's discovery established the modern field of genetics: genes were no longer abstract units (what Mendel had called "elements") but real objects. The fly room's research paved the way for biologists to show that genes make proteins, control development and sometimes cause disease.

Even Darwin came to his conclusions on evolution based on observation, while Morgan shifted the study of life away from simple descriptions. As Nobel prize-winning neuroscientist Eric Kandel wrote, "Morgan's findings about genes and their location on chromosomes helped transform biology into an experimental science."

Morgan's fly boys

During the 1910s and 1920s, Morgan had three outstanding students, nicknamed the 'fly boys'.

One was Hermann Muller, later awarded a Nobel prize for showing that X-rays can be used to artificially trigger mutations. This allowed scientists to figure-out what a gene does based on how mutations disrupt its normal function, a principle still used today.

Another student was Alfred Sturtevant, who devised the method for creating 'genetic maps' to show the location of genes on a chromosome. Maps allow genes for known traits – eye color, say – to serve as markers for pinpointing other genes. Researchers still use this approach to identify bits of DNA associated with diseases and other interesting traits.

Sturtevant's insight was this: if two genes are close together, they're less likely to be separated by crossing-over between a pair of chromosomes, which occurs before a parent's genetic material is passed on to offspring. The frequency of offspring carrying new combinations of traits could therefore be used to measure the relative distance between two genes on a map.

Calvin Bridges was the third fly boy. He impressed Morgan by spotting a mutant insect with vermilion (bright red) eyes instead of the normal deep red. While Sturtevant was color-blind, Morgan called Bridges' eyesight "unusually acute". He was also the lab's inventor, creating a binocular microscope and the agar jelly that replaced bananas.

In 1916, Bridges published a study on 'non-disjunction' – which is what happens when chromosomes fail to properly separate after crossing-over. Entitled 'Non-disjunction as proof of the chromosome theory of heredity', it was the first paper to be published in the newly-launched journal Genetics.

Over three decades, Bridges improved lab techniques and gene mapping. Importantly, by studying patterns of light and dark bands on giant chromosomes in fruit fly salivary glands, he converted the relative positions of genes to real locations. This added actual, physical distances to genetic maps.

The Fly Room

Morgan's fly boys had different views on their experience at Columbia. While Muller believed his ideas were being stolen, Sturtevant claimed the atmosphere was a cordial "give and take". Inspired by the true story, The Fly Room reveals the rivalry and social dynamics within the lab.

Written and directed by former geneticist Alexis Gambis, the movie is based on correspondence between lab members and interviews with Calvin Bridges' daughter Betsey (who died in 2014). It focuses on the relationship between the 10-year-old girl and her father, with flash-forwards to Betsey's later life.

The young Calvin Bridges had a huge quiff of brown hair and looked like a movie star (the actor playing him bears a strong resemblance to Tom Cruise). In The Fly Room, he's a brilliant scientist but relentless womanizer. Bridges died aged 49 of heart failure, thought to be related to syphilis.

The movie includes a witty script and clear scientific messages. One character explains that mutations can be mistakes or lead to improvements, for instance, another mentions that evolution cannot operate without genes.

Such statements occasionally carry an overly educational tone, as if the audience is watching a lecture, but generally The Fly Room is a great example of an arthouse film that communicates science in a subtle way.

After Thomas Hunt Morgan won the 1933 Nobel prize in physiology or medicine "for his discoveries concerning the role played by the chromosome in heredity", he shared the prize money with Alfred Sturtevant and Calvin Bridges.

Morgan's gift funded Betsey Bridges' education. She didn't follow in her father's footsteps, but studied costume design instead of biology. As a 93-year-old Betsey says in a voiceover at the start of the film, "I didn't want to be like him."

I'm an award-winning journalist with a PhD in evolutionary biology. I spent several years at Focus, the BBC's popular science and technology magazine, running the features section and writing about everything from gay genes and internet memes to the science of death and orig...